i9ii] E. Newton Harvey 233 



organisms, especially Spirogyra, to NaOH or KOH varies con- 

 siderably froni day to day and this Variation is possibly correlated 

 with the accumulation o£ excretory products or of traces of other 

 toxic substances in the water. 



The toxicity of all the alkalies studied bears no relation to the 

 degree of dissociation. The order of toxicity for Paratnwcium is 

 NCCsHg)^ (?)3 <Na, K, Ca < Sr, Ba < NH4 < amines. The 

 Order of dissociation is NH4 <N(CH3)3 H < primary and sec- 

 ondary amines < N( €2115)4 < Sr, Ba, Ca, Na, K. This may in 

 large part be understood when we consider that the weak alkalies 

 enter the cell readily and the strong do not. But even among the 

 strong alkalies, Ba and Na, about equally dissociated, the Ba is 

 much more toxic. 



The Order of penetration rate for Elodea [NH4OH more rapidly 

 than primary and secondary amines > NH(CH3)30H > Ba, Sr > 

 Ca, K, Na, N(C2H5)40H] is not the order of diffusion in pure 

 water. Those strong alkalies which most readily affect the cell 

 surface enter most rapidly, and are most toxic. But there is no 

 direct relation between toxicity and penetrating power since the 

 strong alkalies bring about many detrimental changes without en- 

 tering the cell. 



Considering the weak alkalies alone, NH4OH enters Elodea 

 most rapidly, yet is least toxic. Trimethyl amine is less disso- 

 ciated than the primary and secondary amines, yet enters the cell 

 less rapidly; although if we consider each of the two classes of alka- 

 lies as a whole, it is the least dissociated class which penetrates most 

 rapidly. N(C2H5)40H affords excellent confirmation of the rule. 

 The Substitution of four C2H5 groups for four H atoms gives a 

 substance whose degree of dissociation, unlike the lower amines, is 

 comparable with that of the strong inorganic hydroxids, Na or Ba, 

 and correspondingly its power of penetrating cells is likewise limited 

 and comparable with that of Na or Ba. 



According to Overton, ammonia and the primary, secondary and 

 tertiary amines are soluble in lipoids, while tetramethyl ammonium 

 hydroxid is not. There is, then, a relation between lipoid solu- 



* A different strain of Paramoecia was used in testing this alkali and it is 

 possibly out of place in the above series. 



